1. Field of the Invention
The present invention relates to an ice-making device of a refrigerator, and more particularly, to an ice-making device of a refrigerator that is capable of easily separating pieces of frozen ice from an ice tray by twisting the ice tray.
2. Description of the Background Art
FIG. 1 is a perspective view of a general refrigerator and front view showing that a door of the refrigerator is opened.
With reference to FIG. 1, a body of the refrigerator is divided into an upper freezing chamber (F) and a lower cooling chamber (R). The freezing chamber (F) and the cooling chamber (R) are opened and closed by doors 20 and 20xe2x80x2 rotatably combined at the front side of the body 10.
Shelves 30 and 30xe2x80x2 are installed at the inner side of the freezing chamber (F) and the cooling chamber (R) and door baskets 21 and 21xe2x80x2 are installed at the inner side of the doors 20 and 20xc2x0, to keep various food stuffs,
A food stuff or a storage container are received at the shelves 30 and 30xe2x80x2 and at the door baskets 21 and 21xe2x80x2.
An ice-making unit 40 is installed in the freezing chamber to make an ice by concentrating cool air.
An ice storing box 50 is installed at a lower side in the freezing chamber (F), to store pieces of ice made by the ice-making unit 40.
The ice-making unit 40 and the ice storing box 50 are installed in a drawer type in the freezing chamber.
The conventional ice-making device will now be described with reference to FIGS. 2A, 2B and 3.
FIG. 2A is a perspective view showing an ice-making unit in accordance with the conventional art.
As shown in FIG. 2A, the ice-making unit 40 includes a rectangular frame shaped case 41 with an upper and a lower portions opened and an ice tray 42 having a plurality of ice cubes 42a and rotatably installed in the case 41.
The ice cubes 42a of the ice tray 42 is filled with water to make ice. That is, after the ice tray 42 is filled with water and kept in the freezing chamber (F) for a predetermined time, the water filled in the ice cubes 42a is changed to ice in a predetermined shape, thereby making ice.
With reference to FIG. 2B, when the ice tray 42 of the ice-making unit 40 is twisted by being rotated, pieces of ice made in the ice tray 42 can be separated.
That is, with reference to FIG. 3, a rotational shaft 42b is formed at the front side of the ice tray 42, penetrating the case 41 to be protruded outwardly, and a knob 43 is fixed at the front side of the rotational shaft 42b. 
A rotational shaft 42c is formed at a rear side of the ice tray 42 and inserted into the case 41.
As to the ice tray 42, when the knob 43 is rotated, it is rotated inside the case 41 centering around the rotations shafts 42b and 42c. 
A protrusion 41a is formed at the rear inner face of the case 41. The protrusion 41a is to render the ice tray 42 to be twisted by limiting the rotation of the ice tray 42 when the tray 42 is rotated clockwise by more than a predetermined angle.
Accordingly, when the user rotates the knob 43 clockwise, as shown in FIG. 2B, the ice tray 42 is rotated in the case 41 upside down to a degree.
At this time, since the rear portion of the ice tray 42 is caught by the protrusion 41a, it could be hardly rotated any further, but the front portion is rotatable.
In this state, when the user rotates the ice tray 42, the ice tray 42 is twisted, so that pieces of ice frozen in the ice tray 42 are separated from the ice cubes 42d. 
The many pieces of ice separated from the ice cubes 42a fall down into the ice storing box 50 installed at the lower side of the ice-making unit as shown in FIG. 1.
An elastic member 44 is wound at the rotation shaft 42c of the ice tray 42. One side of the elastic member is supported by the protrusion 41a and the other there of is caught by the ice tray 42.
Accordingly, when the ice tray 42 is rotated clockwise, the elastic member 44 receives a compressive force, and in this state, when the user lets go of the knob, the elastic member 44 is restored, rotating the ice tray 42 counterclockwise to restore the ice tray 42 to its original horizontal state.
However, the ice-making device of the conventional art has the following shortcomings.
That is, typically, the ice tray 42 is constructed to be rotated clockwise in consideration of the fact that users are mostly right-handed. And, substantially, rotation counterclockwise is limited by the protrusion 41a. 
With such a structure that the ice tray 42 is rotatable in the uni-direction, it is impossible for the user to select a rotation direction, causing a problem that the user may not determine the rotation direction at his or her own discretion according to a use condition of the user.
For example, for a left-handed user who would rather feel comfortable to rotate the knob 43 counterclockwise, the ice-making unit 40 of the conventional art is much inconvenient to use.
In addition, unlike the case that the ice-making unit 40 is installed at the left side of the freezing chamber (F) as shown in FIG. 1, if the ice-making unit is installed near a hinge of the door 20 at the right side of the freezing chamber, the door 20 should be completely opened, because if the door is not completely opened, when the knob 43 is rotated clockwise, the ice-making unit would be interfered by the door basket 21.
Therefore, an object of the present invention is to provide an ice-making device having an ice tray that can be freely rotated in a desired direction for users"" convenience, thereby improving a convenience of users.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an ice-making device including: a case; an ice tray having a plurality of ice cubes, rotatably installed clockwise and counterclockwise in the case; and a rotation stopping unit provided at the case and the ice tray to limit a rotation of an ice tray clockwise or counterclockwise within a predetermined angle in a state that the ice tray is poised horizontally.
In the ice-making device of the present invention, a knob is protruded at the front side of the ice tray and the case, and the rotation stopping unit is installed at the rear side of the ice tray and the case.
In the ice-making device of the present invention, the rotation stopping unit includes a stopping protrusion protruded from the ice tray and a guide groove formed at the case, for guiding a movement of the stopping protrusion so as to be inserted thereto and limiting a rotation of the ice tray within a predetermined angle.
The ice-making device of the present invention further includes an elastic unit formed between the case and the ice tray to provide an elasticity so that the ice tray can return to a horizontal state after being rotated clockwise or counterclockwise.
In the ice-making device of the present invention, a plurality of stopping protrusions and guide grooves are formed at the ice tray and the case.
In the ice-making device of the present invention, the stopping protrusions includes a first stopping protrusion and a second stopping protrusion having different distances, and the guide grooves include a first guide groove ad a second groove into which the first stopping protrusion and the second stopping protrusion are inserted, respectively.
In the ice-making device of the present invention, one stopping protrusion and one guide groove are formed both at the ice tray and the case.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.